$2{e^ - }\, + \,2{H_2}O\, \to \,{H_2}\, + \,2O{H^ - }$
(valence factor) $H_2=2$
At $NTP$ $22400\,mL$ of $H_2=1\,mole$ of $H_2\,\,112\,mL$ of
${H_2}\, = \,\frac{1}{{22400}}\, \times \,112\, = \,0.005\,mole$ of $H_2$
Moles of $H_2$ produced
$ = \frac{{I\, \times t}}{{96500}}\, \times $ mole ratio
$0.05 = \frac{{I\, \times 965}}{{96500}}\, \times \frac{{1\,\,mole\,\,of\,\,{H_2}}}{{2\,\,mole\,\,of\,\,{e^ - }}}$
$I\,=\,1.0\,A$
$(i)$ $A + e \rightarrow A^{-} ; E^o= -0.24 V$
$(ii)$ $B^{-} + e \rightarrow B^{2-}; E^o = + 1.25 V$
$(iii)$ $C^{-} + 2e \rightarrow C^{3-}; E^o = -1.25 V $
$(iv)$ $D + 2e \rightarrow D^{2-}; E^o = + 0.68 V$
($F = 96,500\;C\;mo{l^{ - 1}}; \,\, R = 8.314\;J{K^{ - 1}}mo{l^{ - 1}})$